Wound healing: effects of closing tension, zyplast, and platelet-derived growth factor

Previous studies have shown that beginning 5 to 7 days from wounding, the tensile strength of wounds closed under tension in rats is significantly higher than the tensile strength of wounds closed without tension. This study evaluated the effects of increased closing tension, zyplast implant (ZI), and human recombinant platelet-derived growth factor (PDGF) on the tensile strength of wounds. Six groups of 12 rats each were divided into two main subsets: wounds were closed without tension in three groups and with high tension of approximately 100 g in the three other groups. In both no-tension and high-tension groups, one subgroup received no intervention (controls), one subgroup received ZI (zyplast controls), and one subgroup received ZI-PDGF (ZI used as a carrier for PDGF). Healing was evaluated by tensile strength determinations at 5 days. For the controls, wounds closed under tension showed a trend toward higher tensile strength, but statistical significance was not reached. Compared with controls, tensile strength was 45% lower in the wounds with ZI and closure with tension (P = .0063) and 38% lower in the wounds with ZI and closure without tension (P = .007). Treatment with ZI-PDGF resulted in 69% higher tensile strengths (P = .049) as compared with ZI controls for wounds closed with tension. This study demonstrated the beneficial effect of PDGF in accelerating healing in wounds closed under tension. Although ZI was able to deliver PDGF to the wound, the use of this substance as a carrier is questioned since it was detrimental to healing.